How to use the pouchdb-promise function in pouchdb-promise

args = clone(args);
    var self = this;
    var tempCB =
      (typeof args[args.length - 1] === 'function') ? args.pop() : false;
    // if the last argument is a function, assume its a callback
    var usedCB;
    if (tempCB) {
      // if it was a callback, create a new callback which calls it,
      // but do so async so we don't trap any errors
      usedCB = function (err, resp) {
        process.nextTick(function () {
          tempCB(err, resp);
        });
      };
    }
    var promise = new Promise(function (fulfill, reject) {
      var resp;
      try {
        var callback = once(function (err, mesg) {
          if (err) {
            reject(err);
          } else {
            fulfill(mesg);
          }
        });
        // create a callback for this invocation
        // apply the function in the orig context
        args.push(callback);
        resp = func.apply(self, args);
        if (resp && typeof resp.then === 'function') {
          fulfill(resp);
        }

function fetchAtt () {
        return new Promise(function (resolve, reject) {
          txn.get(stores.attachmentStore, digest, function (err, oldAtt) {
            /* istanbul ignore if */
            if (err && err.name !== 'NotFoundError') {
              return reject(err)
            }
            resolve(oldAtt)
          })
        })
      }

var newAtt = {};

        if (oldAtt) {
          if (oldAtt.refs) {
            // only update references if this attachment already has them
            // since we cannot migrate old style attachments here without
            // doing a full db scan for references
            newAtt.refs = oldAtt.refs;
            newAtt.refs[ref] = true;
          }
        } else {
          newAtt.refs = {};
          newAtt.refs[ref] = true;
        }

        return new Promise(function (resolve) {
          txn.batch([{
            type: 'put',
            prefix: stores.attachmentStore,
            key: digest,
            value: newAtt
          }]);
          resolve(!oldAtt);
        });
      }

function fetchAttachment (att, stores, opts) {
  var type = att.content_type
  return new Promise(function (resolve, reject) {
    stores.binaryStore.get(att.digest, function (err, buffer) {
      var data
      if (err) {
        /* istanbul ignore if */
        if (err.name !== 'NotFoundError') {
          return reject(err)
        } else {
          // empty
          if (!opts.binary) {
            data = ''
          } else {
            data = binStringToBluffer('', type)
          }
        }
      } else { // non-empty
        if (opts.binary) {

var newAtt = {}

        if (oldAtt) {
          if (oldAtt.refs) {
            // only update references if this attachment already has them
            // since we cannot migrate old style attachments here without
            // doing a full db scan for references
            newAtt.refs = oldAtt.refs
            newAtt.refs[ref] = true
          }
        } else {
          newAtt.refs = {}
          newAtt.refs[ref] = true
        }

        return new Promise(function (resolve) {
          txn.batch([{
            type: 'put',
            prefix: stores.attachmentStore,
            key: digest,
            value: newAtt
          }])
          resolve(!oldAtt)
        })
      }

function fetchAtt() {
        return new Promise(function (resolve, reject) {
          txn.get(stores.attachmentStore, digest, function (err, oldAtt) {
            /* istanbul ignore if */
            if (err && err.name !== 'NotFoundError') {
              return reject(err);
            }
            resolve(oldAtt);
          });
        });
      }

var ajax = function (opts) {
    return new Promise(function (resolve, reject) {
      ajaxCore(opts, wrapError(function (err, res) {
        if (err) {
          return reject(err);
        }
        resolve(res);
      }));
    });
  };
  var updateUser = function (user, opts) {